Cruise tracks and stations

Predefined IBTS squares for sampling by the Norwegian vessel

The map below shows the northern region of the North Sea with ICES IBTS squares. The coloured squares are the ones that were planned to be sampled by the R/V G.O. Sars during the 2020 IBTS survey.

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Cruise track

Cruise tracks from the position log with points indicating start positions for different sampling gear. The points are jittered slightly for better visual representation:

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Sampling depth for trawl hauls

15 bottom trawl hauls were taken during the survey. The trawl hauls covered a total distance of 58.9 km (31.8 nmi).

The sampling stations were located in areas with bottom depths from 95.9 m to 218.9 m, and the fishing depth varied from 96.2 m to 219 m.

Mean fishing depth during trawl hauls

Catch rates - biomass and number per nautical mile trawled for species registered in Sea2Data

Species diversity

A total of 115 species were registered in Sea2Data during the survey.

Number of species identified versus the number of stations sampled

Average catch rate by species for the 20 species with highest catch rates

Bottom trawl

Spatial variation in catches of common species

Pelagic fish

Herring

Sprat

Mackerel

Demersal fish

Haddock

Cod

Whiting

Norway pout

Saithe

Hake

Blackbelly rosefish (Blåkjeft)

Length distributions

The following figures shows the length distribution of individuals sampled during the survey.

Length-age relationships

CTD

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Summary of measurements

34 CTD casts were done during the survey, covering a total depth of 2.7 km.

Variation in temperature and salinity with bathymetry and geographical location

## Density in the water column

## Light in the water column